DNA vaccines for influenza virus: Differential effects of maternal antibody on immune responses to hemagglutinin and nucleoprotein

Maternal antibody is the major form of protection from disease in early lif e when the neonatal immune system is still immature; however, the presence of maternal antibody also interferes with active immunization, placing infa nts at risk for severe bacterial and viral infection. We tested the ability of intramuscular and gene gun immunization with DNA expressing influenza v irus hemagglutinin (HA) and nucleoprotein (NP) to raise protective humoral and cellular responses in the presence or absence of maternal antibody. Neo natal mice born to influenza virus-immune mothers raised full antibody resp onses to NP but failed to generate antibody responses to HA. In contrast, t he presence of maternal antibody did not affect the generation of long-live d CD8(+) T-cell responses to both HA and NP. Thus, maternal antibody did no t affect cell-mediated responses but did affect humoral responses, with the ability to limit the antibody response correlating with whether the DNA-ex pressed immunogen was localized in the plasma membrane or within the cell.